The material I've synthesised is made up of two primary parts at a 1:1 ratio:

  • Part 1: agar, glycerol, water.
  • Part 2: polyurethane resin.

The agar mixture on its own was too soft, so I added the resin to harden the material. Would this material be classified as a hybrid composite? If not, why?

  • $\begingroup$ It is likely a composite. Sinthesys became (unfortunately) a slang to replace "making" "preparation" etc... $\endgroup$ – Alchimista Mar 11 at 11:41

There is a slight deviation in the literature as to what the hybrid composites are. Originally, materials were considered hybrid composites if both inorganic (e.g. clay/silicates as the hydrophilic component) and organic (e.g. organic polymer as the hydrophobic component) constituents were involved in building up the matrix (see e.g. a review [1]).

Another review [2] and the more recent definition from Encyclopedic Dictionary of Polymers [3, p. 373]:

Hybrid Composite n Advanced composite with a combination of different high-strength continuous filaments in the matrix. Also, composite in which continuous and staple fibers are used in the same matrix.

provide a more permissive definition, according to which hybrid composite materials are the materials in which a combination of reinforcing layers from two or more types of fibers is utilized.

With this in mind, in order to provide a definitive answer for yourself, you probably want to do surface imaging (e.g. with AFM or SEM) to prove that really are more than one type of fibers present. If you are planning to publish this data, be prepared that you will be asked to provide rheological data as well.


  1. Wahab, M. A.; Kim, I.; Ha, C.-S. Silica- and Silsesquioxane-Containing Polymer Nanohybrids. In Macromolecules Containing Metal and Metal-Like Elements; Abd-El-Aziz, A. S., Carraher, C. E., Pittman, C. U., Zeldin, M., Eds.; John Wiley & Sons, Inc.: Hoboken, NJ, USA, 2005; pp 133–160. DOI: 10.1002/0471712566.ch6.
  2. Perov, B. V.; Khoroshilova, I. P. Hybrid Composite Materials. In Polymer Matrix Composites; Shalin, R. E., Ed.; Soviet Advanced Composites Technology Series; Springer Netherlands: Dordrecht, 1995; pp 269–304. DOI: 10.1007/978-94-011-0515-6_6.
  3. Encyclopedic Dictionary of Polymers; Gooch, J. W., Ed.; Springer New York: New York, NY, 2011. DOI: 10.1007/978-1-4419-6247-8.
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    $\begingroup$ Thank you. I couldn't exactly find the correlation or significant differences of this material to the description of a hybrid composite, so your information really helped and is appreciated. $\endgroup$ – Henry Mar 12 at 4:14

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